Conventional disc drives include a housing which houses one or more rotatable data storage discs, which store data. Magnetic disc drives, for instance, store magnetic flux reversals on the surface of the disc. As the disc rotates the flux reversals are sensed by a read head which, in turn, generates a read signal indicative of the flux reversals on the disc surface. The flux reversals represent encoded data which is stored on the surface of the disc.
Optical disc drives store data in much the same way, except that instead of using magnetic flux reversals, optical disc drives alter the optical properties of the disc surface in a way which is indicative of the data to be stored. As the disc rotates, an optical transducer generates a read signal indicative of data to be read from the data storage surface on the disc.
In both such disc drives the discs are rotated relative to the transducers so the transducers can read from, or write to, the disc surfaces. In some disc drives, the transducers actually contact the disc surface, as the surface is being accessed, to write or retrieve data. In other disc drives, momentary or intermittent contact is made with the disc surface. In still other disc drives, the data head is attached to a slider which includes an air bearing surface. As the disc rotates, hydrodynamic forces, aerodynamic forces, or a combination of forces, act on the air bearing surface to lift the transducer off the surface of the disc such that the transducer “flies” over the disc surface.
Conventional disc drives must meet certain specifications for physical robustness. Therefore, the disc drives are subjected to physical shocks. The drives are then tested to determine whether the drives operate appropriately during, and/or after, the physical shock is imparted to the disc drive.